Scotopic threshold response and scotopic PII in glaucoma.

PURPOSE

The value of the ERG scotopic threshold response (STR), which is known to originate in the proximal retina and of the near-threshold scotopic PII(B-wave), was studied in glaucoma.

METHODS

Full-field single flashes were presented under scotopic conditions in two subject groups, a glaucoma group (n = 30) and a normal control group (n = 35). The intensity level for evoking STR was where the maximum response occurs, whereas the intensity level for evoking scotopic PII was where the response begins to appear.

RESULTS

The STR is only slightly reduced in glaucoma (P = 0.046), but scotopic PII is significantly diminished (P < 0.0001).

CONCLUSIONS

The relatively intact STR in glaucoma suggests that structures responsible for its generation are less damaged in glaucoma than those responsible for scotopic PII.